Compositions and methods for use in three dimensional model printing

ABSTRACT

Compositions for use in the manufacture of three-dimensional objects including compositions for use as a support and/or release material in the manufacture of the three-dimensional objects are provided. There is thus provided, in accordance with an embodiment of the present invention, a composition suitable for building a three-dimensional object. The compositions may include, inter alia, a curable component, having a functional group, wherein if the functional group is a polymerizable reactive functional group, then the functional group is a (meth)acrylic functional group, a photo-initiator, a surface-active agent and a stabilizer; wherein said composition has a first viscosity of about 50-500 cps at a first temperature, wherein said first temperature is ambient temperature, and a second viscosity lower than 20 cps at a second temperature wherein said second temperature is higher than said first temperature, wherein, after curing, the composition results in a solid form. There is thus provided, in accordance with another embodiment of the present invention, a composition suitable for support in building a three-dimensional object. The compositions may include, inter alia: a non-curable component, a curable component, wherein the non-curable component is not reactive with said curable component, a surface-active agent and a stabilizer; wherein said composition has a first viscosity of about 20-500 cps at a first temperature, wherein said first temperature is ambient temperature, and a second viscosity lower than 20 cps at a second temperature wherein said second temperature is higher than said first temperature, wherein, after irradiation, the composition results in a solid, a semi-solid or liquid material. A method for the preparation of a three-dimensional object by three-dimensional printing is provided in accordance with embodiments of the present invention. Embodiments of the present invention further provide a three-dimensional object prepared according to the methods of the invention.

RELATED APPLICATIONS

This application is a continuation of prior US application Ser. No.10/424,732 filed 29 Apr. 2003, which is a continuation-in-partapplication of U.S. application Ser. No. 09/803,108, filed 12 Mar.,2001, entitled “Compositions And Methods For Use In Three DimensionalModel Printing”, which claims priority of provisional application no.60/188,698, filed 13 Mar. 2000, entitled “Methods And Formulations ForThree-Dimensional Printing”, and provisional application No. 60/195,321filed 10 Apr. 2000, entitled “Methods And Formulations ForThree-Dimensional Printing”, each of which are incorporated in itsentirety by reference herein.

FIELD OF THE INVENTION

The present invention relates to three-dimensional object building ingeneral and to methods and compositions for use in three-dimensionalprinting of complex structures in particular.

BACKGROUND OF THE INVENTION

Three-dimensional printing, which typically works by building parts inlayers, is a process used for the building up of three-dimensionalobjects. Three-dimensional printing is relatively speedy and flexible,allowing for the production of prototype parts, tooling and rapidmanufacturing of three-dimensional complex structures directly from aCAD file, for example.

Using three-dimensional printing may enable a manufactures to obtain afull three-dimensional model of any proposed product before tooling,thereby possibly substantially reducing the cost of tooling and leadingto a better synchronization between design and manufacturing. A lowerproduct cost and improved product quality may also be obtained.

Using three-dimensional printing also enables the direct manufacturingof full three-dimensional objects, thereby substantially reducing costsand leading to a better synchronization between design, production andconsumption (use). A lower product cost and improved product quality maythus also be obtained.

Various systems have been developed for computerized three-dimensionalprinting. In U.S. Pat. No. 6,259,962 to the Assignees of the presentapplication, and incorporated herein by reference, embodiments of anapparatus and a method for three-dimensional model printing aredescribed. The apparatus according to some embodiments in this patentinclude a printing head having a plurality of nozzles, a dispensersconnected to the printing head for selectively dispensing interfacematerial in layers, and curing means for optionally curing each of thelayers deposited. The depth of each deposited layer may be controllableby selectively adjusting the output from each of the plurality ofnozzles.

In U.S. patent application Ser. No. 09/412,618 to the Assignees of thepresent invention, and incorporated herein by reference, embodiments aredescribed including an apparatus and a method for three-dimensionalmodel printing. Some embodiments of this application describe a systemand a method for printing complex three-dimensional models by usinginterface materials having different hardness or elasticity and mixingthe interface material from each of the printing heads to control thehardness of the material forming the three-dimensional model. Theconstruction layers of the model may be formed from interface materialhaving a different (harder) modulus of elasticity than the material usedto form the release (and support) layers, thereby allowing for theforming of complex shapes.

Radiation curable inks are disclosed in, for example, U.S. Pat. Nos.4,303,924, 5,889,084, and 5,270,368. U.S. Pat. No. 4,303,924 discloses,inter alia, radiation curable compositions for jet-drop printingcontaining multi-functional ethylenically unsaturated material,monofunctional ethylenically unsaturated material, a reactive synergist,a dye colorant and an oil soluble salt. U.S. Pat. No. 5,889,084discloses, inter alia, a radiation curable ink composition for ink-jetprinting which includes a cationically photoreactive epoxy or vinylether monomer or, oligomer, a cationic photo-initiator and a coloringagent. U.S. Pat. No. 5,270,368 discloses, inter alia, a UV curable inkcomposition for ink-jet printing including a resin formulation having atleast two acrylate components, a photo-initiator and an organic carrier.

The ink compositions disclosed in these references are typicallyformulated for use in ink-jet printing. Compositions for ink-jetprinting are typically formulated differently from compositions forbuilding three-dimensional objects, and thus have different properties.For example, high viscosity at room temperature is a desirable propertyfor three-dimensional objects, and thus compositions for buildingthree-dimensional objects are typically designed to have a highviscosity at room temperature. In contrast, compositions for ink-jetprinting are designed to have low viscosity at room temperature in orderto function well in the printing process. None of the above-mentionedreferences disclose compositions that are especially formulated forthree-dimensional printing.

Radiation curable compositions for stereolithography are disclosed inU.S. Pat. No. 5,705,316. U.S. Pat. No. 5,705,316 discloses compoundshaving at least one vinyl ether group, which also contain in themolecule at least one other functional group such as an epoxy or anacrylate group; compositions including these compounds; and methods ofproducing three-dimensional objects using these compositions. Thecompounds of U.S. Pat. No. 5,705,316 are complex molecules that are notreadily available and thus need to be especially synthesized, whichincurs additional time and costs.

Thus, there is a need for simple, easily obtainable curablecompositions, that are specially formulated to construct athree-dimensional object. There is further a need for simple, easilyobtainable curable compositions, that are specially formulated toprovide support to a three-dimensional object, by forming support and orrelease layers around the object during its construction. Lastly, thereis a need for methods of constructing a three-dimensional object byusing the above mentioned compositions.

SUMMARY OF THE INVENTION

The present invention relates to compositions for use in the manufactureof three-dimensional objects. The present invention further relates tocompositions for, use as a support and/or release material in themanufacture of the three-dimensional objects. The present inventionfurther relates to a method for the preparation of a three-dimensionalobject by three-dimensional printing, and to a three-dimensional objectobtained by the method.

There is thus provided, in accordance with an embodiment of the presentinvention, a composition for use in the manufacture of three-dimensionalobjects by a method of selective dispensing. The composition mayinclude, inter alia, at least one reactive component, at least onephoto-initiator, at least one surface-active agent, and at least onestabilizer.

The composition has a first viscosity above 50 cps at room temperature,and a second viscosity compatible with ink-jet printers at a secondtemperature, wherein the second temperature is higher than roomtemperature.

In accordance with an embodiment of the present invention, the reactivecomponent is an acrylic component, a molecule having one or more epoxysubstituents, a molecule having one or more vinyl ether substituents,vinylcaprolactam, vinylpyrolidone, or any combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component is an acrylic component. The acrylic component isan acrylic monomer, an acrylic oligomer, an acrylic crosslinker, or anycombination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, an acrylic component andin addition a molecule having one or more epoxy substitutents, amolecule having one or more vinyl ether substituents, vinylcaprolactam,vinylpyrolidone, or any combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, an acrylic component andvinylcaprolactam.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, a molecule having one ormore vinyl ether substitutents.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, a molecule having one ormore epoxy substituents.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, a molecule having one ormore vinyl ether substituents, and a molecule having one or more epoxysubstitutents.

Furthermore, in accordance with an embodiment of the present invention,the photo-initiator is a free radical photo-initiator, a cationicphoto-initiator, or any combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the composition further includes at least one pigment and at least onedispersant. The pigment is a white pigment, an organic pigment, aninorganic pigment, a metal pigment or, a combination thereof. In oneembodiment, the composition further includes a dye.

Furthermore, in accordance with an embodiment of the present invention,the first viscosity of the composition is greater than 80 cps. In oneembodiment, the first viscosity is between 80 and 300 cps. In anotherembodiment, the first viscosity is around 300 cps.

Furthermore, in accordance with an embodiment of the present invention,the second viscosity of the composition is lower than 20 cps at a secondtemperature, which is greater than 60° C. Preferably, the secondviscosity is between 8 and 15 cps at the second temperature, which isgreater than 60° C. In one embodiment, the second viscosity is about 11cps at a temperature around 85° C.

In addition, in accordance with another embodiment of the presentinvention, there is thus provided a composition for use as a supportand/or release material in the manufacture of three-dimensional objectsby a method of selective dispensing. The composition may include, interalia, at least one non-reactive and low toxicity compound, at least onesurface-active agent and at least one stabilizer.

The composition has a first viscosity above 50 cps at room temperature,and a second viscosity compatible with ink-jet printers at a secondtemperature, wherein the second temperature is higher than roomtemperature.

In accordance with an embodiment of the present invention, thecomposition may further include, inter alia, at least one reactivecomponent and at least one photo-initiator. The reactive component is atleast one of an acrylic component, a molecule having one or more vinylether substituents, or the reactive component is a water misciblecomponent that is, after curing, capable of swelling upon exposure towater or to an alkaline or acidic water solution.

Furthermore, in accordance with an embodiment of the present inventionthe reactive component is an acrylic component. The acrylic component isan acrylic oligomer, an acrylic monomer, or a combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, at least one watermiscible component that is, after curing, capable of swelling uponexposure to water or to an alkaline or acidic water solution. The watermiscible component is preferably an acrylated urethane oligomerderivative of polyethylene glycol, a partially acrylated polyololigomer, an acrylated oligomer having hydrophillic substituents, or anycombination thereof. The hydrophilic substituents are preferably acidicsubstituents, amino substituents, hydroxy substituents, or anycombination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, a molecule having one ormore vinyl ether substituents.

Furthermore, in accordance with an embodiment of the present invention,the non-reactive component is polyethylene glycol, methoxy polyethyleneglycol, glycerol, ethoxylated polyol, or propylene glycol.

Furthermore, in accordance with an embodiment of the present invention,the photo-initiator is a free radical photo-initiator, a cationicphoto-initiator, or a combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the first viscosity of the composition is greater than 80 cps. In oneembodiment, the first viscosity is between 80 and 300 cps. In anotherembodiment, the first viscosity is around 200 cps.

Furthermore, in accordance with an embodiment of the present invention,the second viscosity of the composition is lower than 20 cps at a secondtemperature, which is greater than 60° C. Preferably, the secondviscosity is between 8 and 15 cps at the second temperature, which isgreater than 60° C. In one embodiment, the second viscosity is about 11cps at a temperature around 85° C.

In addition, there is thus provided, in accordance with an embodiment ofthe present invention, a method for preparation of a three-dimensionalobject by three-dimensional printings. The method according to anembodiment includes:

-   -   dispensing a first interface material from a printing head, the        first interface material may include, inter alia, at least one        reactive component, at least one photo-initiator, at least one        surface-active agent and at least one stabilizer; dispensing a        second interface material from the printing head, the second        interface material may include, inter alia, at least one        non-reactive and low toxicity compound, at least one        surface-active agent, and at least one stabilizer, combining the        first interface material and the second interface material in        pre-determined proportions to produce construction layers for        forming the three-dimensional object.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the first interface material is an acryliccomponent, a molecule having one or more epoxy substituents, a moleculehaving one or more vinyl ether substituents, vinylpyrolidone,vinylcaprolactam, or any combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the first interface material may include,inter alia, an acrylic component. The acrylic component is an acrylicmonomer, an acrylic oligomer, an acrylic crosslinker, or any combinationthereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the fist interface material may include, interalia, an acrylic component and in addition a molecule having one or moreepoxy substituents, a molecule having one or more vinyl ethersubstituents, vinylcaprolactam, vinylpyrolidone, or any combinationthereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the first interface material may include,inter alia, an acrylic component and vinylcaprolactam.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the first interface material is a moleculehaving one or more vinyl ether substituents.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the first interface material is a moleculehaving one or more epoxy substituents.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the first interface material may include,inter alia, a molecule having one or more epoxy substituents, and amolecule having one or more vinyl ether substituents.

Furthermore, in accordance with an embodiment of the present invention,the first interface material may further include, inter alia, at leastone pigment and at least one dispersant. The pigment is a white pigment,an organic pigment, an inorganic pigment, a metal pigment or acombination thereof. In one embodiment, the first interface material mayfurther, include, inter alia, a dye.

Furthermore, in accordance with an embodiment of the present invention,the method may further include the step of curing the first interfacematerial.

Furthermore, in accordance with an embodiment of the present invention,the second interface material further may include, inter alia, at leastone reactive component and at least one photo-initiator. The reactivecomponent is at least one of an acrylic component, a molecule having oneor more vinyl ether substituents, or the reactive component is a watermiscible component that is, after curing, capable of swelling uponexposure to water or to an alkaline or acidic water solution.

Furthermore, in accordance with an embodiment of the present inventionthe reactive component is an acrylic component. The acrylic component isan acrylic oligomer, an acrylic monomer, or a combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component may include, inter alia, at least one watermiscible component that is, after curing, capable of swelling uponexposure to water or to an alkaline or acidic water solution. The watermiscible component is preferably an acrylated urethane oligomerderivative of polyethylene glycol, a partially acrylated polyololigomer, an acrylated oligomer having hydrophillic substituents, or anycombination thereof. The hydrophilic substituents are preferably acidicsubstituents, amino substituents, hydroxy substituents, or anycombination thereof.

Furthermore, in accordance with an embodiment of the present invention,the reactive component of the second interface material may include,inter alia, a molecule having one or more vinyl ether substituents.

Furthermore, in accordance with an embodiment of the present invention,the non-reactive component is polyethylene glycol, methoxy polyethyleneglycol, glycerol, ethoxylated polyol, or propylene glycol.

Furthermore, in accordance with an embodiment of the present invention,the photo-initiator of the first interface material and optionally ofthe second interface material is a flee radical photo-initiator, acationic photo-initiator or any combination thereof.

Furthermore, in accordance with an embodiment of the present invention,the method may further, include the step of irradiating or curing thesecond interface material.

Furthermore, in accordance with an embodiment of the present invention,the first interface material and the second interface material have adifferent modulus of elasticity and a different strength. In oneembodiment, the first interface material has a higher modulus ofelasticity and a higher strength than the second interface material.

Furthermore, in accordance with an embodiment of the present invention,the method may further include the step of forming a multiplicity ofsupport layers for supporting the object. In one embodiment, the supportlayers are formed by combining the first interface material and thesecond interface material in pre-determined proportions. In oneembodiment, the support layers have the same modulus of elasticity andthe same strength as the construction layers. In another embodiment, thesupport layers have a lower modulus of elasticity and a lower strengththan the construction layers.

Furthermore, in accordance with an embodiment of the present invention,the method may further include the step of combining the first interfacematerial and the second interface material in pre-determined proportionsto form a multiplicity of release layers for releasing the supportlayers from the object. In one embodiment, the release layers have alower modulus of elasticity and a lower strength than the constructionlayers and the support layers.

Furthermore, in accordance with an embodiment of the present invention,the first interface material and the second interface material each havea first viscosity at room temperature, and a second viscosity compatiblewith ink-jet printers at a second temperature, which may be the same ordifferent, wherein the second temperature is higher than roomtemperature.

In addition, there is thus provided, in accordance with anotherembodiment of the present invention, a three-dimensional objectcomprised of a core consisting of a multiplicity of construction layers.The construction layers are prepared by combining pre-determinedproportions of the first interface material and the second interfacematerial, described hereinabove.

Furthermore, in accordance with an embodiment of the present invention,the object may further include a multiplicity of support layers forsupporting the core. In one embodiment, the support layers are preparedby combining pre-determined proportions of the first interface materialand a second interface material In one embodiment, the support layershave the same modulus of elasticity and the same strength as theconstruction layers. In another embodiment, the support layers have alower modulus of elasticity and a lower strength than the constructionlayers.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the object may further include a multiplicity of releaselayers for releasing the support layers from the core. In oneembodiment, the release layers are positioned between the Support layersand the construction layers. The release layers are prepared bycombining predetermined proportions of the first interface material anda second interface material. In one embodiment, the release layers havea lower modulus of elasticity and a lower strength than the constructionlayers and the support layers.

One embodiment of the present invention provides a composition suitablefor building a three-dimensional object, the composition may include,inter alia, a curable component, having a functional group, wherein ifthe functional group is a polymerizable reactive functional group, thenthe functional group is a (meth)acrylic functional group, aphoto-initiator, a surface-active agent and a stabilizer, wherein thecomposition has a first viscosity of about 50-500 cps at a firsttemperature, wherein the first temperature is ambient temperature, and asecond viscosity lower than 20 cps at a second temperature wherein thesecond temperature is higher than the first temperature, wherein, aftercuring, the composition results in a solid form.

One embodiment of the present invention provides a composition suitablefor support in building a three-dimensional object, the composition mayinclude, inter alia, a non-curable component, a curable component,wherein the non-curable component is not reactive with the curablecomponent, a surface-active agent and a stabilizer, wherein thecomposition has a first viscosity of about 20-500 cps at a firsttemperature, wherein the first temperature is ambient temperature, and asecond viscosity lower than 20 cps at a second temperature wherein thesecond temperature is higher than the first temperature, wherein, afterirradiation, the composition results in a solid, a semi solid or aliquid material.

One embodiment of the present invention provides a composition suitablefor, support in building a three-dimensional object, the composition mayinclude, inter alia, a non-curable component, a curable (meth)acryliccomponent, wherein the non-curable component is not reactive with thecurable component, a surface-active agent, a free radicalphoto-initiator and a stabilizer; wherein the composition has a firstviscosity of about 20-500 cps at a first temperature, wherein the firsttemperature is ambient temperature, and a second viscosity lower than 20cps at a second temperature wherein the second temperature is higherthan the first temperature, wherein, after irradiation, the compositionresults in a solid, a semi solid or a liquid material.

One embodiment of the present invention further provides a compositionsuitable for support in building a three-dimensional object, thecomposition may include, inter alia, at least one non-curable component,at least one curable component including a molecule having one or moreepoxy substituents, wherein the non-curable component is not reactivewith the curable component, at least one surface-active agent, at leastone cationic photo-initiator and at least one stabilizer; wherein thecomposition has a first viscosity of about 20-500 cps at a firsttemperature, wherein the first temperature is ambient temperature, and asecond viscosity lower than 20 cps at a second temperature wherein thesecond temperature is higher than the first temperature, wherein, afterirradiation, the composition results in a solid, a semi solid or aliquid material.

One embodiment of the present invention further provides a method forthe preparation of a three-dimensional object by three-dimensionalprinting, the method may include the steps of dispensing a firstcomposition suitable for building a three-dimensional object from adispenser, the first composition may include a curable component, havinga functional group, wherein if the functional group is a polymerizablereactive functional group, then the functional group is a (meth)acrylicfunctional group, a photo-initiator, a surface-active agent, and astabilizer, dispensing a second composition suitable for support inbuilding a three-dimensional object from a dispenser, the secondcomposition may include a non-curable component, a curable component,wherein the non-curable component is not reactive with the curablecomponent, a surface-active agent and a stabilizer; combining the firstcomposition and the second composition in pre-determined proportions toproduce a multiplicity of construction layers for forming thethree-dimensional object, whereby the first composition is curedresulting in a solid form, and whereby the second composition isirradiated or, cured resulting in a liquid, a solid or a semi-solidform.

One embodiment of the present invention further provides athree-dimensional object comprised of a multiplicity of constructionlayers, wherein the construction layers are prepared by combiningpre-determined proportions of a first composition and a secondcomposition according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with theappended drawings in which:

FIG. 1 is a schematic illustration of an embodiment of athree-dimensional printing system;

FIG. 2 is an elevational view of a three-dimensional object, constructedin accordance with an embodiment of the present invention; and

FIG. 3 is a schematic illustration of an embodiment of a method for thepreparation of three-dimensional object by three-dimensional printing.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to compositions for use in the manufactureof three-dimensional objects, and to compositions for use as supportand/or release material in the manufacture of three-dimensional objects.The present invention further relates to a method for the preparation ofa three-dimensional object by three-dimensional printing, using theabove-mentioned compositions, and to a three-dimensional object obtainedby the method.

The composition for use in the manufacture of the three-dimensionalobjects may include, inter, alia, at least one reactive component, atleast one photo-initiator, at least one surface-active agent and atleast one stabilizer. The composition may be formulated so as to becompatible for use with ink-jet printers and to have a viscosity at roomtemperature above 50 cps.

The composition for use as a support and/or second interface material inthe manufacture of the three-dimensional objects may include, interalia, at least one non-reactive and low-toxicity component, at least onesurface-active agent and at least one stabilizer. The composition mayfurther contain at least one reactive component and at least onephoto-initiator. The composition is formulated so as to be compatiblefor use with ink-jet printers and to have a viscosity at loomtemperature above 50 cps.

The compositions will be described in further detail below.

The three-dimensional object of the present invention may be builtusing, for example, a three-dimensional printing system similar toembodiments of U.S. patent application Ser. No. 09/412,618, assigned tothe Assignees of the present application and incorporated herein byreference, although other suitable three-dimensional printers may beused. A three-dimensional printing system is shown in FIG. 1, to whichreference is now made. FIG. 1 is an illustration of a three-dimensionalprinting system, generally designated 10, which includes one or moreprinting heads, referenced 12, and at least two dispensers generallyreferenced 14 and individually referenced 14 a and 14 b, containinginterface materials, generally referenced 16 and individually referenced16 a and 16 b, respectively. Other components, and other sets ofcomponents, may be used.

Printing head 12 has a plurality of ink-jet type nozzles 18, throughwhich interface materials 16 a and 16 b are jetted. In one embodiment ofthe present invention, first dispenser 14 a is connected to a first setof nozzles, referenced 18 a, and second dispenser 14 b is connected to asecond set of nozzles, referenced 18 b, Thus first interface material 16a is jetted through nozzles 18 a, and second interface material 16 b isjetted through nozzles 18 b. Alternatively, in another embodiment (notshown), the three-dimensional printing system may include at least twoprinting heads. The first printing head is connected to first dispenser14 a and is used to jet first interface material 16 a; and the secondprinting head is connected to second dispenser 14 b is used to jetsecond interface material 16 b.

The three-dimensional printing system 10 further includes a controller20, a Computer Aided Design (CAD) system 22, curing unit 24, andoptionally a positioning apparatus 1. The controller 20 is coupled tothe CAD system 22, curing unit 24, positioning apparatus 1, printinghead 12 and each of the dispensers 14. Control may be effected by otherunits than shown, such as one or more separate units.

The three-dimensional object being produced (28) is built in layers, thedepth of each layer typically being controllable by selectivelyadjusting the output from each of the ink-jet nozzles 18.

By combining or mixing materials from each of the dispensers, whereineach dispenser contains interface material having a different hardness,it is possible to adjust and control the hardness of the materialforming the three-dimensional object being produced. Thus, by combiningthe first and second interface materials being output from each of thedispensers, respectively, different parts of the three-dimensionalobject having a different modulus of elasticity and a different strengthmay be produced.

As used hereinafter, the term “strength” is used as a relative term toindicate the difference in modulus of elasticity among interfacematerials. The strength of a material may be described, for example, byreference to its modulus of elasticity, which may be defined as: “theratio of stress to its corresponding strain under given conditions ofload, for materials that deform elastically, according to Hooke's law”.

In accordance with one embodiment of the present invention, the firstdispenser 14 a contains a first interface material 16 a, referred tohereinafter as the “first interface material” or 0 “first composition”,and the second dispenser 14 b contains a second interface material 16 b,referred to hereinafter as the “second interface material” or “secondcomposition”. The first interface material has a different Warder)modulus of elasticity and a greater strength than the second interfacematerial. By combining the first interface material and the secondinterface material, different layers of the three-dimensional objecthaving a different modulus of elasticity and a different strength may beproduced, such as, for example, a model or “construction” layer(otherwise known as a model construction), a support layer (otherwiseknown as a support construction) and a release layer (otherwise known asa release construction), as defined hereinbelow. In accordance withembodiments of the present invention, each layer of materials depositedby the apparatus during the printing process, may include a combinationof model constructions, support constructions and/or releaseconstructions, according to the requirements of the three-dimensionalobject being printed. Thus, when referring herein to constructionlayers, support layers and/or release layers, any or all of these may bepart or parts comprising a single ‘whole layer’ printed by the printingapparatus during the printing process.

For example, combining the first interface material and the secondinterface material forms a multiplicity of construction layers, whichare defined as the layers constituting the three-dimensional object.Multiplicity, as used hereinafter, refers to a number which is one orgreater.

Further, combining the first interface material and the second interfacematerial may form a multiplicity of support layers, which are defined asthe layers supporting the three-dimensional object, and not constitutingthe three-dimensional object.

Further, combining the first interface material and the second interfacematerial may form a multiplicity of release layers, which are defined asthe layers (not constituting the three-dimensional object) forseparating the three-dimensional object layer from layers such as thesupport layers. The release layers typically have a lower modulus ofelasticity and a lower strength than the construction layers and thesupport layers.

In one embodiment of the present invention, the support layers aredesigned substantially exactly as the construction layers, and thus havesubstantially the same modulus of elasticity and substantially the samestrength as the construction layers. In this way, the constructionlayers form a core, and the support layers look like the negativeprinting of the core. The release layers are positioned between theconstruction layers and the support layers, and are used to separate theconstruction layers from the support layers.

In one embodiment of the present invention, the support layers have alower modulus of elasticity and a lower strength than the constructionlayers. The support layers may be separated from the construction layersby taking advantage of their weaker properties, as will be explained indetail below. Alternatively, the support layers may be separated fromthe construction layers by positioning release layers between theconstruction layers and the support layers.

In order to more clearly define the present invention, reference is nowmade to FIG. 2, which is a three-dimensional model of a wineglass,generally referenced 30. This three-dimensional model is printed usingthe ink-jet type printing system of FIG. 1. combining the firstinterface material and the second interface material to form amultiplicity of construction layers 32 which make up wine glass 30.

The construction layers 32 of wineglass 30 need to be supportedexternally, such as in the area referenced 34. Furthermore, an internalvoid, referenced 36, needs to be formed during printing. Thus amultiplicity of support layers 38, formed by combining the firstinterface material and the second interface material, are printed.

Furthermore, combination of the first interface material and the secondinterface material forms a multiplicity of release layers 40. In oneembodiment of the present invention, release layers 40 are positionedbetween construction layers 32 and support layers 38. Generally, releaselayers 40 have a different (lower) modulus of elasticity than supportlayers 38 and construction layers 32. Thus release layers 40 may be usedto separate support layers 38 from construction layers 32.

The present invention, which will now be described in detail, providescompositions suitable for use as the first interface and as the secondinterface material.

The first interface material and second interface material of thepresent invention are especially designed and formulated for building athree-dimensional object using three-dimensional printing. Accordingly,in accordance with an embodiment of the present invention, the firstinterface material and the second interface material each have a firstviscosity at room temperature, and a second viscosity compatible withink-jet printers at a second temperature, which may be the same ordifferent, wherein the second temperature is higher than roomtemperature, which is defined as about 20-30° C.

In one embodiment of the present invention, the first and the secondinterface materials are designed to have increased viscosity at roomtemperature, which is defined as about 20-30° C. In another embodiment,the first and second interface material have a viscosity greater than 50cps at room temperature, In another embodiment, the viscosity may bebetween 80 and 300 cps. In another embodiment, the first and the secondinterface material may have a viscosity of around 300 cps at roomtemperature.

In one embodiment of the present invention, the first interface materialand the second interface material may have a second viscosity compatiblewith ink-jet printing, at a second temperature which may be higher thanroom temperature. In another embodiment, a composition compatible withink-jet printing may have a low viscosity, for example, below 20 cps atthe printing temperature, in order to function properly in the printingprocess. In another embodiment, the first interface material and thesecond interface material, upon heating, have a viscosity preferablybelow 20 cps that may enable the construction of the three-dimensionalobject under heat. In one embodiment of the present invention, thetemperature typically used to build the three-dimensional model of thepresent invention is higher than 60° C. In another embodiment, thetemperature may be about 85° C. In one embodiment of the presentinvention, the first and second interface materials may have a viscosityof 8-15 cps at a temperature great than 60° C. In another embodiment,the first and second interface materials may have a viscosity of 11 cpsat a temperature of about 85° C.

Having this viscosity, the first and second interface material in oneembodiment may be distinguished from prior art formulations designed forink-jet printing, which have low viscosity at room temperature, thetemperature at which the printing is normally conducted. High viscosityat room temperature is a desirable property for three-dimensionalobjects, a feature that is lacking in the prior art formulations Ofcourse, other embodiments may have other viscosities.

First Interface Material

The first interface material (typically, the model material) is acomposition suitable for building a three-dimensional object. Thecomposition may be formulated to give, after curing, a solid material.In one embodiment, this invention describes a composition that after,curing results in a solid material, with mechanical properties thatpermit the building and handling of that three-dimensional object. In aanother embodiment, this invention provides a composition that uponcuring results in a solid elastomer like material, with mechanicalproperties that permit the building and handling of thethree-dimensional object.

One embodiment of the present invention provides a first interfacematerial of the present invention may include, inter alia, at least onereactive component, at least one photo-initiator; at least onesurface-active agent and at least one stabilizer.

One embodiment of the present invention provides a composition suitablefor building a three-dimensional object, the composition may include,inter alia, a curable component, having a functional group, wherein ifthe functional group is a polymerizable reactive functional group, thenthe functional group is a (meth)acrylic functional group, aphoto-initiator, a surface-active agent and a stabilizer, wherein thecomposition has a first viscosity of about 50-500 cps at a firsttemperature, wherein the first temperature is ambient temperature, and asecond viscosity lower than 20 cps at a second temperature wherein thesecond temperature is higher than the first temperature, wherein, aftercuring, the composition results in a solid form.

In one embodiment of the present invention, the first temperature is aroom temperature. In another, embodiment, the room temperature isbetween 20-30° C. In another embodiment, the first temperature isambient temperature. In another embodiment, ambient temperature isbetween 10-40° C. In another embodiment, ambient temperature is between15-35° C. In another embodiment, ambient temperature is between 20-30°C.

In one embodiment of the present invention, the second temperature ishigher than 40° C. In another embodiment, the second temperature ishigher than 50° C. In another embodiment, the second temperature ishigher than 60° C. In another embodiment, the second temperature ishigher than 70° C.

In one embodiment of the present invention, the curable component is areactive component, which is able to undergo polymerization. In oneembodiment of the present invention, the curable component may be a(meth)acrylic monomer, a (meth)acrylic oligomer, a (meth)acryliccrosslinker, or any combination thereof.

In one embodiment of the present invention, the curable component may bea combination of a mono-functional monomer and a di-functional oligomer.

In one embodiment of the present invention, the mono-functional monomeris a high Glass Transition Temperature mono-functional monomer. Inanother embodiment, the di-functional oligomer is a low Glass TransitionTemperature di-functional oligomer. The term Glass transitiontemperature (Tg) is defined as the temperature at which a polymerchanges from hard and brittle to soft and pliable material.

In one embodiment of the present invention, the Glass TransitionTemperature of the mono-functional monomer may be higher than 60° C. Inanother, embodiment, the Glass Transition Temperature of themono-functional monomer may be higher than 70° C. In another embodiment,the Glass Transition Temperature of the mono-functional monomer may bein the range of 70-110° C.

In one embodiment of the present invention, the Glass TransitionTemperature of the di-functional oligomer may be lower, than 40° C. Inanother embodiment, the Glass Transition Temperature of thedi-functional oligomer may be lower than 30° C. In another embodiment,the Glass Transition Temperature of the di-functional oligomer may be inthe range of 20-30° C.

One embodiment of the present invention provides a composition whereinthe Glass Transition Temperature of the mono-functional monomer ishigher than 70° C. and wherein the Glass Transition Temperature of thedi-functional oligomer is lower than 40° C.

In one embodiment of the present invention, the composition may includeat least 20% of the high Glass Transition Temperature mono-functionalmonomer. In another embodiment, the composition may include at least 30%of the high Glass Transition Temperature mono-functional monomer. Inanother embodiment, the composition may include at least 40% of the highGlass Transition Temperature mono-functional monomer. In anotherembodiment, the composition may include between 20-40% of the high GlassTransition Temperature mono-functional monomer. In another embodiment,the composition may include between 30-60% of the high Glass TransitionTemperature mono-functional monomer.

In one embodiment of the present invention, the composition may includeabout 20% of the low Glass Transition Temperature di-functionaloligomers. In another embodiment, the composition may include about 40%of the low Glass Transition Temperature di-functional oligomers. Inanother embodiment, the composition may include between 20-40% of thelow Glass Transition Temperature di-functional oligomers. In another,embodiment, the composition may include at least 20% of the low GlassTransition Temperature di-functional oligomer. In another embodiment,the composition may include not more than 40% of the low GlassTransition Temperature di-functional oligomer.

In one embodiment of the present invention, the composition may includeat least 40% of the high Glass Transition Temperature mono-functionalmonomers and at least 20% of the low Glass Transition Temperaturedi-functional oligomer.

In one embodiment of the present invention, the composition may includeat least 20% of the high Glass Transition Temperature mono-functionalmonomers and not more than 40% of the low Glass Transition Temperaturedi-functional oligomer.

An acrylic monomer is a functional acrylated molecule which may be, forexample, esters of acrylic acid and methacrylic acid. Monomers may bemono-functional or multi-functional (fort example, di-, tri-,tetra-functional, and others). An example of an acrylic mono-functionalmonomer for the present invention is phenoxyethyl acrylate, marketed bySattomer under the trade name SR-339. An example of an acrylicdi-functional monomer is propoxylated (2) neopentyl glycol diacrylate,marketed by Sartomer under the trade name SR-9003.

An acrylic oligomer is a functional acrylated molecule which may be,for, example, polyesters of acrylic acid and methacrylic acid. Otherexamples of acrylic oligomers ate the classes of urethane acrylates andurethane methacrylates. Urethane-acrylates are manufactured fromaliphatic or aromatic or cycloaliphatic diisocyanates or polyisocyanatesand hydroxyl-containing acrylic acid esters. An example is aurethane-acrylate oligomer marketed by Cognis under the trade namePhotomer-6010.

An acrylic crosslinker is a molecule which may provide enhancedcrosslinking density. Examples of such resins are DitrimethylolpropaneTetra-acrylate (DiTMPTTA), Pentaerythitol Tetra-acrylate (TEITA),Dipentaerythitol Penta-acrylate (DiPEP). In one embodiment of thepresent invention, the composition may further includes, inter alia, acurable component, which is a molecule having one or more epoxysubstituents, a molecule having one or more vinyl ether substituents,vinylcaprolactam, vinylpyrolidone, or any combination thereof. In oneembodiment of the present invention, the composition may furtherincludes, inter alia, vinylcaprolactam. Other curable components mayalso be used.

The first interface material may also include a curable component whichis, for example, a molecule having one or more vinyl ether substituents.In one embodiment of the present invention, the concentration ofcomponent that includes a molecule having one or more vinyl ethersubstituents is in the range of 10-30%. In another embodiment, theconcentration is 15-20%. In another embodiment, the concentration is15%. Of course, other concentrations, and other ranges, can be used.Conventional vinyl ether monomers and oligomers which have at leastvinyl ether group are suitable. Examples of vinyl ethers are ethyl vinylether, propyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether,2-ethylhexyl vinyl ether, butyl vinyl ether, ethyleneglocol monovinylether, diethyleneglycol divinyl ether, butane diol divinyl ether, hexanediol divinyl ether, cyclohexane dimethanol monovinyl ether and the like.An example of a vinyl ether for the present invention is 1,4 cyclohexanedimethanol divinyl ether, marketed by ISP under the trade name CHVE.

In one embodiment of the present invention, the first interface materialmay also include a curable component which is a molecule having one ormore epoxy substituents. In one embodiment of the present invention,conventional epoxy monomers and oligomers which have at least one oxanemoiety may be used. Non-limiting examples of suitable epoxy containingmolecules are displayed in Table 1 below (note other suppliers may beused for suitable materials): TABLE 1 Examples of epoxy-containingcurable component Trade Name Type of Material Supplier ERL-4299 or UVR-Bis-(3,4 cyclohexylmethyl) Union Carbide 6128 adipate UVR-6105 and3,4-epoxy cyclohexylmethyl-3,4- Union Carbide UVR-6110 epoxycyclohexylcarboxylate D.E.R732 Aliphatic epoxy, Polyglycol Dow chemicalsdiglycidyl ether Vinylcyclohexene 1,2 epoxy-4-vinylcyclohexane UnionCarbide Monoxide D.E.N431 Epoxy novolac resin Dow corning UVR-62161,2-epoxy hexadecane Union Carbide UVI-6100 Cycloaliphatic epoxidediluent Union Carbide Vikoflex 7170 Fullyl epoxidized soy bean oil ElfAtochem, INC., ERL-4221D 3,4-epoxy cyclohexylmethyl Union Carbide3,4-epoxy cyclohexane carboxylate

In one embodiment of the present invention, the first interface materialmay include any combination of an acrylic component as definedhereinabove, a molecule having one or more epoxy substituents as definedhereinabove, a molecule having one or more vinyl ether substituents asdefined hereinabove, vinylcaprolactam and vinylpyrolidone.

In one embodiment of the present invention, the curable component of thefirst interface material includes, inter, alia, an acrylic monomer, anacrylic oligomer, an acrylic crosslinker and vinylcaprolactam. Inanother, embodiment, the curable component includes an acrylic componentas defined hereinabove and a molecule having one or more epoxysubstituents as defined hereinabove. In another embodiment, the curablecomponent of the first interface material includes an acrylic componentas defined hereinabove and a molecule having one or more vinyl ethersubstituents as defined hereinabove. In another embodiment, the curablecomponent in the first interface material includes a molecule having oneor more vinyl ether substituents as defined hereinabove, and a moleculehaving one or more epoxy substituents as defined hereinabove.

The photo-initiation of the first interface material and of the secondinterface material may be the same or different, and is a free radicalphoto-initiator, a cationic photo-initiator; or any combination thereof.

The free radical photo-initiator may be any compound that produces afree radical on exposure to radiation such as ultraviolet of visibleradiation and thereby initiates a polymerization reaction. Non-limitingexamples of some suitable photo-initiators include benzophenones(aromatic ketones) such as benzophenone, methyl benzophenone, Michler'sketone and xanthones; acylphosphine oxide type photo-initiators such as2,4,6-trimethylbenzolydiphenyl phosphine oxide (IMPO),2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide (IEPO), andbisacylphosphine oxides (BAPO's); benzoins and bezoin alkyl ethers suchas benzoin, benzoin methyl ether and benzoin isopropyl ether and thelike. Examples of photo-initiators are alpha-amino ketone, marketed byCiba Specialties Chemicals Inc. (Ciba) under the trade name Irgacure907, and bisacylphosphine oxide (BAPO's), marketed by Ciba under thetrade name I-819.

The free-radical photo-initiator may be used alone or in combinationwith a co-initiator. Co-initiators are used with initiators that need asecond molecule to produce a radical that is active in the UV-systems.Benzophenone is an example of a photoinitiator that requires a secondmolecule, such as an amine, to produce a curable radical. Afterabsorbing radiation, benzophenone reacts with a ternary amine byhydrogen abstraction, to generate an alpha-amino radical which initiatespolymerization of acrylates. Non-limiting example of a class ofco-initiators are alkanolamines such as triethylamine,methyldiethanolamine and triethanolamine.

Suitable cationic photo-initiators fox the present invention includecompounds which form aprotic acids or Bronstead acids upon exposure toultraviolet and/or visible light sufficient to initiate polymerization.The photo-initiator used may be a single compound, a mixture of two ormore active compounds, or a combination of two or more differentcompounds, i.e. co-initiators. Non-limiting examples of suitablecationic photo-initiators are aryldiazonium salts, diaryliodonium salts,triarylsulphonium salts, triarylselenonium salts and the like. In oneembodiment, a cationic photo-initiator for the present invention may bea mixture of triarylsolfonium hexafluoroantimonate salts marketed byUnion Carbide as UVI-6974.

In one embodiment of the present invention, the composition suitable forbuilding a three-dimensional object, may further include a curablecompound, which is a sulfur-containing component. In one embodiment ofthe present invention, the sulfur containing component is betamercaptopropionate, mercaptoacetate, alkane thiols or any combinationthereof. The addition of sulfur-containing components may significantlyenhances the composition reactivity. At levels of about 5% ofsulfur-containing component a significant reactivity enhancement isachieved. The mechanical properties of the composition may be determineddepending on the sulfur-containing component used. The reactivityenhancement achieved by the use of sulfur-containing component, enablesthe incorporation in the polymerization reaction of nonsulfur-containing components, which would not easily polymerizeotherwise. Molecules having unsaturated double bonds, for example, lowmolecular weight polybuthadiene, is polymerized in the claimedcompositions when it contains an appropriate sulfur-containingcomponent. For example, a basic composition will contain 15% lowmolecular, weight unsaturated molecule, 5% sulfur-containing component,15% mono-functional monomer, 15% di-functional monomer and the restother curable components according to the intended photopolymerproperties. An example of a sulfur-containing component for the presentinvention is trimethylolpropane tri(3-mercaptopropionate), manufacturedby BRUNO BOCK Chemische Fabrik GMBH & CO. Other suitable substances maybe used.

In one embodiment of the present invention, the composition suitable forbuilding a three-dimensional object, further includes, inter alia, a lowmolecular weight polymer. An example of a low molecular weight polymerfor the present invention is Styrene-Butadiene-Methacrylate blockcopolymers (KRATON D), manufactured by Dow Corning. Other, suitablesubstances may be used.

In one embodiment of the present invention, the composition suitable forbuilding a three-dimensional object, further includes, inter alia, afiller.

The term filler is defined as an inert material added to a polymer, apolymer composition or other material to modify their properties and/orto adjust quality of the end products. The filler may be an inorganicparticle, for example calcium carbonate, silica and clay. Of courseother fillers substances may be used.

Fillers may be introduced in to polymer compositions in order to reduceshrinkage during polymerization or during cooling, for example to reducethe coefficient of thermal expansion, increase strength, increasethermal stability reduce cost and/or adopt theological properties. Theuse of standard fillers has also some drawbacks such as reduction ofelasticity and an increase in viscosity. Additionally, large diameterfillers (>5 micron) are not appropriate for ink-jet applications.

Nano-particles fillers are especially useful in applications requiringlow viscosity such as ink-jet applications. Compositions containing asmuch as 30% nano-particle fillers are feasible, whereas the sameconcentration of more standard and higher diameter fillers (˜>1 micron)produce at such concentration viscosities which are too high for ink-jetapplications. In one embodiment of the present invention, thenano-particle filler containing composition is clear. The composition isclear (e.g. transparent) since it contains no visual fillers. Incontrast, compositions containing more standard and higher diametervisible fillers (˜>1 micron), are not clear.

In one embodiment of the present invention, the composition optionallymay contain pigments. In another embodiment, the pigment concentrationmay be lower than 35%. In another embodiment, the pigment concentrationmay be lower than 15%.

In one embodiment of the present invention, the filler may includeparticles such as particles having an average diameter of less than 100nm. In another embodiment, the filler may include particles having adiameter in the range of 10-100 nm. In another embodiment, the fillermay include particles having a diameter in the range of 20-80 nm. Inanother embodiment, the filler may include particles having a diameterin the range of 10-50 nm. In another embodiment, the filler may includeparticles having a diameter smaller than 10 nm. Examples of fillers thatmay be used in the composition are HIGHLINK OG (particle size spanningbetween 9 nm to 50 run), manufactured by Clariant, and NANOCRYL(particle size below 50 nm), manufactured by Hanse Chemie. Othersuitable substances may be used.

It was discovered that phase separation may be induced during theradiation curing process of the present method. In one embodiment of thepresent invention, the phase separation may produce a clear material,which may have improved impact-resistance. This composition, uponbending develops micro-cracks, before breaking. These micro-cracks caneasily be distinguished due to the whitening of the stress area orstress line. In another embodiment, the phase separation results in anon-clear cured material. It was discovered that certain combinations ofUV curable components induce phase separation during curing. Suchcompositions are clear before curing and may be clear, hazy or opaqueafter curing. Such compositions have an improved impact strength andhigher elongation, when compared to similar compositions, which do notshow such phase separation. For example, it was discovered that theaddition of some silicon containing oligomers, at levels as low as 5%,to the above described composition, may already create a substance whichinduces such phase separation. An example of a silicon acrylatedmolecule is Ebecryl 350, manufactured by UCB Chemicals. Of course othersubstances may be used.

One embodiment of the present invention provides a composition furtherincludes a phase separation inducing component. In another embodiment,the phase separation inducing component is a silicon oligomer. Inanother embodiment, the concentration of the silicon oligomer is atleast 5%.

In one embodiment of the present invention, phase separation may beinduced during curing, resulting in a non-clear cured material. Certaincombinations of UV curable composition suffer a phase separation processduring curing. Such compositions are clear before curing and hazy towhite after curing. Such compositions have an improved impact strengthand higher elongation, when compared to similar compositions, which donot suffer from such phase separation. For example, the addition of somesilicon containing oligomers, at levels as low as 5%, to the abovedescribed composition, may create a substance which suffers from suchface separation.

In one embodiment of the present invention, the first viscosity is about80-500 cps. In another embodiment, the first viscosity is about 300 cps.Of course, compositions having other, viscosities may be used.

In one embodiment of the present invention, the second viscosity islower than 20 cps and wherein the second temperature is higher than 60°C. In another embodiment, the second viscosity is between 10 and 17 cpsand wherein the second temperature is higher than 60° C. In anotherembodiment, the second viscosity is between 10 and 17 cps and whereinthe second temperature is about 70-110° C. In another embodiment, thesecond viscosity is between 12 and 15 cps and wherein the secondtemperature is about 70-90° C. Of course, compositions having otherviscosities may be used.

Other components of the first interface material and the secondinterface material of the present invention are surface-active agentsand inhibitors (typically, thermal stabilizers). A surface-active agentmay be used to reduce the surface tension of the formulation to thevalue required for jetting or for printing process, which is typicallyaround 30 dyne/cm. An example of a surface-active agent for the presentinvention is silicone surface additive, marketed by Byk Chemie under thetrade name Byk 307. Inhibitors may be employed in the formulations ofthe first interface material and the second interface material to permitthe use of the formulation at high temperature, for example around 85°C., without causing thermal polymerization.

In one embodiment of the present invention, the composition may furtherinclude, inter alia, at least one pigment and at least one dispersant.In one embodiment of the present invention, the pigment may be a whitepigment. In another embodiment, the pigment may be an organic pigment.In another embodiment, the pigment may be an inorganic pigment. Inanother embodiment, the pigment may be a metal pigment or a combinationthereof. In one embodiment of the present invention, the composition mayfurther include, inter alia, a dye. An example of a white pigment forthe present invention is organic treated titanium dioxide, marketed byKemira Pigments under the trade name UV TITAN M160 VEG. An example of anorganic pigment for the present invention is an organic pigment marketedby Elementis Specialities under the trade name Tint Aid PC 9703.Examples of dispersants for the present invention are dispersantsincluding a copolymer with acidic groups marketed by Byk Chemie underthe trade name Disperbyk 110, and a dispersant including a highmolecular weight block copolymer with pigment affinic groups, marketedby Byk Chemie under the trade name Disperbyk 163. Furthermore, in oneembodiment of the present invention, combinations of white pigments anddyes are used to prepare colored resins. In such combinations, the whitepigment may have at least a double task: 1) to impart opacity, and 2) toshield the dye from UV radiation, to prevent bleaching of the resin.Thus, in accordance with one embodiment of the present invention, thefirst interface material further includes a dye. The dye may be chosenso as not to interfere with the curing efficiency of the formulation ofthe first interface material. The dye may be any of a broad class ofsolvent soluble dyes. Some non-limiting examples are azo dyes which areyellow, orange, brown and red; anthiaquinone and triarylmethane dyeswhich are green and blue; and azine dye which is black. An example of adye for the present invention is Solvent Red 127, marketed by SpectraColors Corp. under the trade name Spectiasol RED BLG.

The relative proportions of the different components of the firstinterface material may vary. In one embodiment of the present invention,the first interface material includes the following components: 50%acrylic oligomer(s), 30% acrylic monomer(s), 15% acrylic crosslinker, 2%photoinitiator, surface active agent, pigments, and stabilizers. Ofcourse, other compositions may be used.

Non-limiting examples of formulations of the first interface materialare provided hereinbelow in Tables 24, to which reference is now made.Tables 2 and 3 illustrate examples of possible formulations of the firstinterface material. Table 4 illustrates examples of coloredformulations, which include pigments, dispersants and dyes, as definedhereinabove. To any of the examples in Tables 2 and 3 may be added thecombination of the colorants of Table 4. The individual substances,suppliers, combinations, etc., are given by way of example only. TABLE 2Examples of Characteristic Formulation Components of First InterfaceMaterial Function in the # Trade Name Chemical Type formulation supplierA Photomer- Urethane Acrylate Oligomer Oligomer Cognis 6010 B SR-339Phenoxy ethyl Acrylate monomer Sartomer C SR-351 TrimethylolCross-linker Sartomer propane triacrylate D Irgacure alpha-Amino KetoneFree radical Ciba 907 photo-initiator Specialties Chemical Inc., E BPBenzophenone Free radical Satomer photo-initiator F Triethanol TernaryAmine Free radical Sigma Amine Coinitiator G Byk 307 Silicone SurfaceAdditive Surface agent Byk Chemie H MEHQ 4-Methoxy phenol InhibitorSigma I Cyracure 3,4 Epoxycyclohexylmethyl- Epoxy Union UVR-61103,4-epoxycyclohexylcarboxylate oligomer Carbide J UVI-6974 MixedTriarylsulfonium Cationic Union Hexafluoroantimonate Saltsphoto-initiator Carbide K CHVE 1,4-cyclohexane dimethanol Vinyl EtherISP divinyl ether Monomer L UN TITAN Organic Treated Titanium Whitepigment KEMIRA M160 VEG Dioxide PIGMENTS M Disperbyk Copolimer withacidic groups Pigment Byk Chemie 110 Dispersant N Spectrasol Solvent Red127 Dye Spectra RED BLG Colors Corp., O Tint Aid Organic pigment OrganicElementis PC 9703 pigment Specialties P Disperbyk High molecular weightblock Pigment Byk Chemie 163 copolymer with pigment affinic Dispersantgroups Q V-Cap Vinylcaprolactam Monomer ISP R V-Pyrol VinylpyrolidoneMonomer ISP S Silicon Ebecryl 350 Phase UCB acrylated separationChemicals oligomer promoter T Trimethylol Sulfur-containing compoundCrosslinker BRUNO propane BOCK tri(3- Chemische mercaptopropionate)Fabrik HMBH & CO.,

TABLE 3 Examples of Possible Formulation Compositions of First InterfaceMaterial Example A B C D E F G H I J K Q R S T 1 X X X X X X 2 X X X X X3 X X X X X 4 X X X X X 5 X X X X X X X 6 X X X X X X 7 X X X X X X 8 XX X X X X 9 X X X X X X 10 X X X X X X X 11 X X X X X 12 X X X X X X X13 X X X X X X X X X X X 14 X X X X X X X 15 X X X X X X X 16 X X X X XX X 17 X X X X X X X

TABLE 4 Examples of colored formulations of first interface materialExample L M N O P 16 X X 17 X X X 18 X X X X 19 X X 20 X X X

In one embodiment of the present invention, the formulation of the firstinterface material is presented in entry No. 14 of Table No. 3.According one embodiment of the present invention, the first interfacematerial includes:

-   -   an acrylic oligomer, which may be any acrylic oligomer as        defined hereinabove, and which may be an urethane acrylate        oligomer;    -   an acrylic monomer, which may be any acrylic monomer as defined        hereinabove, and which may be phenoxy ethyl acrylate;    -   an acrylic crosslinker, which may be any acrylic crosslinker as        defined hereinabove, and which may be trimethylol propane        triacrylate;    -   a radical photo-initiator, which may be any radical        photo-initiator as defined hereinabove, and which may be        alpha-amino ketone;    -   a surface agent, which may be a silicone surface additive;    -   an inhibitor, which may be 4-methoxyphenol; and    -   vinylcaprolactam.        Second Interface Material

The second interface material (in one embodiment, the support material)is a composition typically formulated to support the building of athree-dimensional object. In one embodiment of the present invention,the second interface material is formulated to form a release layer topermit a manual easy separation or cleaning of the three-dimensionalobject from its support.

In one embodiment of the present invention, the second interfacematerial may be one of two different principle kinds: 1) a liquidmaterial lacking any curable groups that remains liquid even afterirradiation. In one embodiment, the liquid is water, miscible and iseasily washed out by water, or with other material. In anotherembodiment the liquid is non water-immiscible and is easily washed outby water or by a water detergent solution and 2) a solid or semi-solidmaterial that is formulated as a weak curable material. The solid orsemi-solid material, when cured, may be capable of swelling in water orin alkaline or acidic water or water detergent solution. Thus, whencured, the second interface material may swell and almost break uponexposure to water, or in alkaline or, acidic water or water detergentsolution, with minimum manual work required. In both cases the secondinterface material is formulated so as to permit fast, easy andefficient removal of the second interface material and cleaning of thethree-dimensional model from its support.

In one embodiment, the second interface material of the presentinvention may include, inter alia, at least one non-reactive and lowtoxicity compound, at least one surface-active agent and at least onestabilizer.

One embodiment of the present invention provides a composition suitablefor support in building a three-dimensional object, the composition mayinclude, inter alia, a non-curable component, a curable component,wherein the non-curable component is not reactive with the curablecomponent, a surface-active agent, and a stabilizer; wherein thecomposition has a first viscosity of about 20-500 cps at a firsttemperature, wherein the first temperature is ambient temperature, and asecond viscosity lower than 20 cps at a second temperature wherein thesecond temperature is higher than the first temperature, wherein, afterirradiation, the composition results in a semi solid material. Ofcourse, compositions having other viscosities may be used.

In one embodiment of the present invention, the composition suitable forsupport in building a three-dimensional object, after irradiation, mayresult in a semi-solid material. In another embodiment, the semi-solidmaterial may be gel type material. In another embodiment, thecomposition may result in a liquid material. In another embodiment, thecomposition results in a solid material that is formulated as a weakcurable material. In another embodiment, upon irradiation, thecomposition results in a material that is capable of swelling in wateror in alkaline or acidic water. Thus, when irradiated, the secondinterface material swells and almost breaks upon exposure to water, withminimum manual work required.

In one embodiment of the present invention, the second interfacematerial is formulated so as to permit fast, easy and efficient removalof the second interface material and cleaning of the three-dimensionalmodel from its support.

In one embodiment of the second invention, the curable component is areactive component. In another embodiment of the present invention, thereactive component can undergo polymerization. According to oneembodiment, the second interface material is formulated as a curablecomposition that is capable of solidifying upon curing. In oneembodiment of the second invention, the curable components may besimilar to those used in the first interface material, but chosenspecifically to give a hydrophillic cured resin, with weak mechanicalproperties. Thus, upon curing, a solid composition is formed that isweak and can be easily pulverized for example by hand or using water.

In one embodiment of the present invention, the curable component may bea (meth)acrylic component. In another embodiment, the (meth)acryliccomponent may be a (meth)acrylic monomer. In another embodiment, the(meth)acrylic component may be a (meth)acrylic oligomer. In anotherembodiment, the (meth)acrylic component may be a (meth)acryliccrsosslinker. In another embodiment, the (meth)acrylic component may beany combination of a (meth)acrylic monomer, a (meth)acrylic oligomer anda (meth)acrylic crsosslinker.

In one embodiment of the present invention, the composition may furtherinclude, inter alia, at least one photo-initiator . . . In oneembodiment of the present invention, the photo-initiator may a freeradical photo-initiator, a cationic photo-initiator, or any combinationthereof. The photo-initiator may be any photo-initiator, as definedabove.

One embodiment of the present invention provides a composition suitablefor support in building a three-dimensional object, the composition mayinclude, inter alia, a non-curable component, a curable (meth)acryliccomponent, wherein the non-curable component is not reactive with thecurable component, a surface-active agent, a free radicalphoto-initiator and a stabilizer, wherein the composition has a firstviscosity of about 20-500 cps at a first temperature, wherein the firsttemperature is ambient temperature, and a second viscosity lower than 20cps at a second temperature wherein the second temperature is higherthan the first temperature, wherein, after irradiation, the compositionresults in a solid, a semi-solid or a liquid material.

In one embodiment of the present invention, the composition may furtherinclude, inter alia, water. In one embodiment of the present invention,the composition further, includes a water miscible component that is,after irradiation or curing, capable of dissolving or swelling uponexposure to water, to an alkaline or acidic water solution or to waterdetergent solution. In another embodiment, the water miscible componentis a (meth)acrylated urethane oligomer derivative of polyethyleneglycol, a partially (meth)acrylated polyol oligomer, a (meth)acrylatedoligomer having hydrophillic substituents, polyethylene glycol mono ordi (meth)acrylated, acrylamide, Acryloylmorpholine(ACMO) or anycombination thereof. In another embodiment, the hydrophilic substituentsare acidic substituents, amino substituents, hydroxy substituents, ionicsubstituents or any combination thereof.

Non-limiting examples of acrylic components for use in the secondinterface material of the present invention are polyethylene glycolmonoacrylate, marketed by Laporte under the trade name Bisomer PEA6,polyethylene glycol diacrylate, marketed by Sartomer under the tradename SR-610, methoxypolyethyleneglycole 550 monomethacrylate, and thelike.

In one embodiment of the present invention, the curable component of thesecond interface material may be a water miscible component that is,after curing, capable of swelling upon exposure to water or to analkaline or acidic water solution. Non-limiting examples of watermiscible components for the present invention are an acrylated urethaneoligomer derivative of polyethylene glycol—polyethylene glycol urethanediacrylate, a partially acrylated polyol oligomer, an acrylated oligomerhaving hydrophillic substituents, or any combination thereof. Thehydrophilic substituents are acidic substituents, amino substituents,hydroxy substituents, or any combination thereof. An example of anacrylated monomer with hydrophillic substituents is betha-carboxyethylacrylate, which contains acidic substituents.

In one embodiment of the present invention, the curable component of thesecond interface material may also be a molecule having one or morevinyl ether substituents, which may be any of the compounds as definedhereinabove. In one embodiment of the present invention, theconcentration of component that includes a molecule having one or morevinyl ether substituents is in the range of 10-30%. In anotherembodiment, the concentration is 15-20%. In another embodiment, theconcentration is 15%. Other concentrations may also be used. An exampleof vinyl ether for the second interface material is 1,4-cyclohexanedimethanol divinyl ether, marketed by ISP under the trade name CHVE.Other molecules having one or more vinyl ether, substituents may beused.

In one embodiment of the present invention, the curable component of thesecond interface material is an acrylic oligomer. In another embodiment,the curable component of the second interface material is a combinationof an acrylic component as defined hereinabove and a water misciblecomponent as defined hereinabove. In another embodiment, the curablecomponent of the present invention is a combination of an acryliccomponent as defined hereinabove and a molecule having one or more vinylether substituents, as defined hereinabove. In another embodiment, thecurable component of the present invention is a combination of a watermiscible component as defined hereinabove, and a molecule having one ormore vinyl ether substituents, as defined hereinabove. Othercombinations may also be used.

In one embodiment of the present invention, the composition furtherincludes, inter alia, a sulfur-containing component. In anotherembodiment, the sulfur containing component is beta mercaptopropionate,mercaptoacetate, alkane thiols or any combination thereof. Thesulfur-containing component may be any sulfur-containing component, asdefined above.

In one embodiment of the present invention, the non-curable component ofthe second interface material is a non-curable component. In anotherembodiment the non-curable component is non-polymerizing component. Inanother embodiment, the non-curable component is a low toxicitycompound. In another embodiment, the non-curable component is a watermiscible one. In another, embodiment, the non-curable component is anon-water miscible one. In one embodiment of the present invention, thenon-curable component is chosen to enhance the water-swelling rate, andto reduce the mechanical strength of the second interface material. Highwater diffusion rate is desirable in order to minimize the time neededfor the water cleaning process of the three-dimensional model.Non-limiting examples of non-curable components for the presentinvention are polyethylene glycol marketed by Aldrich under the tradename PEG 400, methoxypolyethylene glycol marketed by Aldrich under thetrade name methoxycarbowax 500 and 1000, propylene glycol and paraffinoil. Other examples axe ethoxylated polyols and glycerol.

In one embodiment of the present invention, the second interfacematerial is formulated as a liquid. The liquid formulation is anon-curable composition that remains liquid even after radiationexposure. Thus, the liquid formulation includes non-reactive componentsand does not include reactive components that are capable uponsolidifying upon curing. In one embodiment of the present invention, thematerial may be water miscible, and may easily be washed out with water.

In one embodiment of the present invention, the non-curable component ispolyethylene glycol, methoxypolyethylene glycol, glycerol, ethoxylatedpolyol, propylene glycol or any combination thereof. In anotherembodiment, the non-curable component is a non-water miscible compound.In another embodiment, the non-water miscible compound is paraffin oil.Other non-curable substances may be used.

One embodiment of the present invention further provides a compositionsuitable for support in building a three-dimensional object, thecomposition may include, inter alia, at least one non-curable component,at least one curable component including, inter alia, a molecule havingone or more epoxy substituents, wherein the non-curable component is notreactive with the curable component, at least one surface-active agent,at least one cationic photo-initiator and at least one stabilizer,wherein the composition has a first viscosity of about 20-500 cps at afirst temperature, wherein the first temperature is ambient temperature,and a second viscosity lower than 20 cps at a second temperature whereinthe second temperature is higher than the first temperature, wherein,after irradiation, the composition results in a semi solid material.

In one embodiment of the present invention, the first temperature is aroom temperature. In another embodiment, the room temperature is between20-30° C. In another embodiment, the first temperature is ambienttemperature. In another embodiment, ambient temperature is between10-40° C. In another embodiment, ambient temperature is between 15-35°C. In another embodiment, ambient temperature is between 20-30° C.

In one embodiment of the present invention, the second temperature ishigher than 40° C. In another embodiment, the second temperature ishigher than 50° C. In another embodiment, the second temperature ishigher than 60° C. In another embodiment, the second temperature ishigher than 70° C.

Besides swelling, another characteristic of the support upon exposure towater or to an alkaline or acidic water or water detergent solution maybe the ability to break down during exposure to water or to an alkalineor acidic water solution. In one embodiment of the present invention,because the second interface material is made of hydrophilliccomponents, during the swelling process, internal forces appear andcause fractures and breakdown of the cured second interface material.

In addition, the second interface material may be at least partiallywater-soluble. At least part of the second interface material is may becompletely water soluble/miscible. During the removal of the supportand/or release layers, the water soluble/miscible components areextracted out with water.

In addition, in one embodiment of the present invention, the secondinterface material liberates bubbles upon exposure to water, or to analkaline water or acidic water solution. The bubbles are intended tohelp in the process of removal of the support and/or release layers fromthe construction layers.

In one embodiment of the present invention, the bubbles may be liberatedby a bubble releasing substance (BRS) that is present in the watersolution that is used to clean out the three-dimensional object. Such asubstance may be a carbonate or bicarbonate, for example sodiumbicarbonate (SBC). During the swelling process, at least part of the SBCis introduced or absorbed into the second interface material, where itis transformed into carbon dioxide gas (CO₂) and a water-soluble salt.The trigger for the production of CO₂ may be the reaction of the SBCwith an acid functionality present in the second interface material.Such acid functionality may be introduced as part of the secondinterface material formulation or introduced later, after curing, usingan acid water solution. For example, the first step may be to put thethree-dimensional object with its support in a water solution containinga SBC, then to place the same object in an acidic solution. The acidwill start to decompose the SBC and produces gas (bubbles).

In another embodiment, the substance that liberates gas is alreadypresent in the formulation of the second interface material. Forexample, the second interface material may contain calcium carbonate asa solid filler. In that case, the trigger is the introduction of thesecond interface material in a water or acidic solution.

It should be clear that a BRS is not limited to a sodium bicarbonate orcalcium carbonate and an acidic water solution. Other chemical reagentsand reactions may be used to achieve the same result—the production ofbubbles inside the matrix of the second interface material. For example,the SBC may be any alkaline metal or alkaline earth metal carbonate orbicarbonate.

In one embodiment of the present invention, the non-curable component isa non-water miscible compound. In another embodiment, the non-watermiscible compound is paraffin oil.

In one embodiment of the present invention, the composition furtherincludes, inter alia, a filler. In another embodiment, the fillersincludes particles having a diameter of less than 1 micron.

In one embodiment of the present invention, the composition furtherincludes a low molecular weight polymer.

In one embodiment of the present invention, the first viscositycomposition suitable for support in building a three-dimensional objectis about 30-200 cps.

In one embodiment of the present invention, the second viscosity of thecomposition suitable for support in building a three-dimensional objectis lower than 20 cps. In another embodiment, the second viscosity isbetween 10 and 17 cps. In another embodiment, the second viscosity isbetween 12 and 16 cps.

Having these viscosities, the first and second interface material may bedistinguished from certain prior art formulations designed for ink-jetprinting, which may have low viscosity at room temperature, thetemperature at which the printing is typically conducted. High viscosityat room temperature may be a desirable property for three-dimensionalobjects, a feature that may be lacking in the prior art formulations.

In one embodiment of the present invention, the composition furtherincludes, inter alia, a component able to produce gas upon exposure towater or to an alkaline or acidic water solution. In another embodiment,the component is sodium bicarbonate, calcium bicarbonate or acombination thereof. Other suitable substances may be used.

In one embodiment of the present invention, the second interfacecomposition further includes, inter alia, a pigment, a dye or acombination thereof. In another embodiment, the pigment is a whitepigment, an organic pigment, an inorganic pigment, a metal pigment or acombination thereof.

Examples of formulations of the second interface material ale providedhereinbelow in Table 5 and Table 6, to which reference is now made.Tables 5 and 6 display various formulations that are suitable for use asthe second interface material. The individual substances, suppliers,combinations, etc., are given by way of example only. TABLE 5 Examplesof Characteristic Formulation Components of Second Interface MaterialFunction in the # Trade Name Chemical Type formulation Supplier A SR-610Polyethylene Glycole (600) Oligomer Sartomer Diacrylate B Bisomer PEA6Polyethylene Glycole Water swelling/ Laport monoacrylate sensitiveOligomer C PEG 400 Polyethylene Glycole 400 Polymer Aldrich (hydrophilicand plasticizer) D Irgacure 907 alpha-Amino Ketone Free radical Cibaphoto-initiator Specialties Type I Chemical Inc., E BP Benzophenone Freeradical Satomer photo-initiator Type II F Triethanol Ternary Amine Freeradical Aldrich Amine Coinitiator for Type II photo- initiator G Byk 307Silicone Surtface Additive Surface agent Byk Chemie H MEHQ 4-Methoxyphenol Inhibitor Sigma (thermal stabilizer) I PEG UA Polyethylene glycolurethane Water Home made diacrylate swelling/sensitive oligomer J APPartially acrylated polyol Water swelling/ Home made sensitive oligomerK Betha-CEA Betha-caboxyethyl acrylate Acidic monomer M CHVE1,4-Cyclohexane dimethanol Vinyl ether ISP divinyl ether monomer N Tonepolyol Caprolactone polyol Polyol Union 0301 (plasticizer) Cabide OParaffin oil Paraffin oil plasticizer Oldrich P methoxycarbomethoxypolyethylene glycol Polymer wax 500 and (hydrophilic and 1000plasticizer) Q SR 506 Isoborny Acrylate monomer Cray Valley

TABLE 6 Examples of Possible Formulation Compositions of SecondInterface Material Example A B C D E F G H I J K L M O Q N 1 X X X X X 2X X X X X X 3 X X X X X 4 X X X X X X 5 X X X X X X 6 X X X X X X X 7 XX X X 8 X X X X X 9 X X X X X X 10 X X X X X 11 X X X X 12 X X X X X X13 X X X X X X 14 X X X X X X X X X X 15 X X X

A formulation of the second interface material is presented in entry No.3 of Table 6. According to this embodiment of the present invention, thesecond interface material includes:

-   -   a water swelling oligomer, which may be any water swelling        oligomer as defined hereinabove, and which may be polyethylene        glycol;    -   a non-curable component, which may be any non-curable component        as defined hereinabove, and which may be polyethylene glycole;    -   a radical photo-initiator, which may be any radical        photo-initiator as defined hereinabove, and which may be        alpha-amino ketone;        -   a surface agent, which may be a silicone surface additive;            and    -   an inhibitor, which may be 4-methoxyphenol.

Another formulation of the second interface material is presented inentry No. 4 of Table 6. According to this embodiment of the presentinvention, the second interface material includes:

-   -   a water swelling oligomer, which may be any water swelling        oligomer as defined hereinabove, and which may be polyethylene        glycole monoacrylate;    -   a non-curable component, which may be any non-curable component        as defined hereinabove, and which may be polyethylene glycole;    -   a radical photo-initiator, which may be any radical        photo-initiator as defined hereinabove, and which may be        benzophenone;    -   a co-initiator, which may be any co-initiator as defined        hereinabove, and which may be triethanolamine;        -   a surface agent, which may be a silicone surface additive;            and    -   an inhibitor, which may be 4-methoxyphenol.

The first interface material and the second interface material aresuitable for use in, for example, the method for, three-dimensionalpainting which is described in U.S. patent application Ser. No.09/412,618, assigned to the Assignees of the present application and isincorporated herein by reference. Other methods may be used.

Briefly, the method according to one embodiment includes:

-   -   dispensing a first interface material from a printing head;        -   dispensing a second interface material from the printing            head; and    -   combining the first interface material and the second interface        material in pre-determined proportions to a produce a        multiplicity of construction layers for forming the        three-dimensional model.

The method (FIG. 3) according to an embodiment of the present inventionincludes dispensing a first composition suitable for, building athree-dimensional object from a dispenser (102), dispensing a secondcomposition suitable for support in building a three-dimensional objectfrom a dispenser, (104), combining the first composition and the secondcomposition in predetermined proportions to produce a multiplicity ofconstruction layers for forming the three-dimensional object (106),curing the first composition resulting in a solid form (108), andirradiating or curing second composition resulting in a liquid, a solidor a semi-solid form (110). Of course, the method may include othersteps or series of steps.

One embodiment of the present invention further provides a method forthe preparation of a three-dimensional object by three-dimensionalprinting, the method may include the steps of dispensing a firstcomposition suitable fox building a three-dimensional object from adispenser; the first composition may include, inter alia, a curablecomponent, having a functional group, wherein if the functional group isa polymerizable reactive functional group, then the functional group isa (meth)acrylic functional group, a photo-initiator, a surface-activeagent; and a stabilizer, dispensing a second composition suitable forsupport in building a three-dimensional object from a dispenser; thesecond composition may include a non-curable component, a curablecomponent, wherein the non-curable component is not reactive with thecurable component, a surface-active agent and a stabilizer, combiningthe first composition and the second composition in predeterminedproportions to produce a multiplicity of construction layers for formingthe three-dimensional object, whereby the first composition is curedresulting in a solid form, and whereby the second composition isirradiated or cured resulting in a liquid, a solid or, a semi-solidform.

In one embodiment of the present invention, the method may furtherinclude the step of generating data for a predetermined combination ofthe first composition and the second composition to produce amultiplicity of support layers for supporting the three-dimensionalobject.

In one embodiment of the present invention, the method may furtherinclude the step of generating data for, a pre-determined combination ofthe first composition and the second composition to produce amultiplicity of release layers for releasing the three-dimensionalobject from the support layers.

In one embodiment of the present invention, the first composition andthe second composition are dispensed simultaneously. In anotherembodiment, the first composition and the second composition aredispensed sequentially. In another embodiment, the first composition isdispensed first. In another embodiment, the second composition isdispensed first. In another embodiment, more than one first compositionis used. In another embodiment, the more than one second composition isused.

In accordance with one embodiment of the present invention, the methodfurther includes the step of curing the first interface material.Further, when the second interface material includes a curablecomponent, the method may further include the step of curing the secondinterface material. Curing may be carried out for example, as describedin U.S. patent application Ser. No. 09/412,618. For example, the curingmethod is by radiation, such as Ultraviolet (UV) and/or Visible (Vis)and/or Infra Red (1R) and/or UV-Vis radiation and/or Electron Beam (EB).In one embodiment of the present invention, the curing method is UV-Visradiation. Other suitable curing methods may be used.

In operation, in order to obtain layers of different modulus ofelasticity and a different strength, the first interface material andthe second interface material are combined in predetermined proportions.For example, in order to obtain layers having a higher modulus ofelasticity and a higher strength such as the construction layers, asuitable combination that contains mostly the first interface materialmay be used. Further, in order to obtain layers having a lower modulusof elasticity and a lower strength such as the release layers, asuitable combination that includes mostly the second interface materialmay be used.

By way of example, in order to produce the construction layers and/orthe support layers, a combination that includes 90-100% of the firstinterface material and 0-10% of the second interface material may beused. Further, in order to produce the release layers, a combinationthat includes 0-10% of the first interface material and 90-100% of thesecond interface material may be used. In another embodiment, in orderto produce support layers that have a lower, modulus of elasticity and alower strength than the construction layers, a combination that includes30-70% of the first interface material and 70-30% of the secondinterface material may be used.

Thus a three-dimensional object is produced which is included of a coreconsisting of a multiplicity of construction layers. The constructionlayers are formed by combining predetermined proportions of the firstinterface material and the second interface material.

One embodiment of the present invention further provides athree-dimensional object comprised of a multiplicity of constructionlayers, wherein the construction layers are prepared by combiningpredetermined proportions of a first composition and a secondcomposition according to the invention. In another embodiment thethree-dimensional object is comprised of a core consisting of amultiplicity of construction layers, wherein the construction layers areprepared by combining pre-determined proportions of a first compositionand a second composition according to the invention.

One embodiment of the present invention provides a three-dimensionalobject including the composition according the invention.

In one embodiment of the present invention, the three-dimensional objectfurther includes a multiplicity of support layers for supporting thecore. The support layers are prepared by combining predeterminedproportions of the first interface material and the second interfacematerial. The support layers may be designed exactly like toconstruction layers, or may be designed to be weaker (lower modulus ofelasticity) than the construction layers.

In one embodiment of the present invention, the three-dimensional objectmay further include a multiplicity of support layers for supporting thecore, wherein the support layers are prepared by combining predeterminedproportions of the first composition and the second composition. Inanother embodiment, the support layers support the construction layers.In another, embodiment, the support layers have the same strength as theconstruction layers. In another embodiment, the support layers have thesame modulus of elasticity as the construction layers. In anotherembodiment, the support layers have a lower modulus of elasticity and/ora lower strength than the construction layers.

In one embodiment of the present invention, the three-dimensional objectfurther includes a multiplicity of release layers for releasing thesupport layers from the construction layers. In one embodiment of thepresent invention, the release layers are positioned between the supportlayers and the construction layers. The release layers are prepared bycombining predetermined proportions of the first interface material andthe second interface material.

In one embodiment of the present invention, the three-dimensional objectmay further include a multiplicity of release layers for, releasing thesupport layers from the core, wherein the release layers are positionedbetween the support layers and the construction layers; wherein therelease layers are prepared by combining pre-determined proportions ofthe first composition and the second composition. In another embodiment,the release layers have a lower modulus of elasticity and/or a lowerstrength than the construction layers and the support layers.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed herein above and that numerous modifications, all of whichfall within the scope of the present invention, exist. Rather, the scopeof the invention is defined by the claims which follow:

1. A composition suitable for support in building a three-dimensionalobject, said composition comprising: a non-curable component; a curablecomponent; wherein said non-curable component is not relative with saidcurable component, a surface-active agent; and a stabilizer; whereinsaid composition has a first viscosity of about 20-500 cps at a firsttemperature, wherein said first temperature, is ambient temperature, anda second viscosity lower than 20 cps at a second temperature whereinsaid second temperature is higher than said first temperature; wherein,after irradiation, said composition results in a solid, a semi solid ofa liquid material.
 2. The composition according to claim 1, furthercomprising water.
 3. The composition according to claim 1, furthercomprising at least one photo-initiator.
 4. The composition according toclaim 1, wherein said curable component is a (meth)acrylic component. 5.The composition according to claim 4, wherein said (meth)acryliccomponent is a (meth)acrylic monomer, a (meth)acrylic oligomer, a(meth)acrylic crosslinker or a combination thereof.
 6. The compositionaccording to claim 1, further comprising a water miscible component thatis, after irradiation or curing, capable of dissolving or swelling uponexposure to water, to an alkaine of acidic water solution or to waterdetergent solution.
 7. The composition according to claim 6, whereinsaid water miscible component is a (meth)acrylated urethane oligomerderivative of polyethylene glycol, a partially (meth)acrylated polyololigomer, a (meth)acrylated oligomer having hydrophillic substituents,polyethylene glycol mono or di (meth)acrylated, acrylamide or anycombination thereof.
 8. The composition according to claim 7, whereinsaid hydrophilic substituents are acidic substituents, aminosubstituents, hydroxy substituents, ionic substituents or anycombination thereof.
 9. The composition according to claim 1, furthercomprising a molecule having one or more vinyl ether substituents. 10.The composition according to claim 1, wherein said non-curable componentis polyethylene glycol, methoxypolyethylene glycol, glycerol,ethoxylated polyol, propylene glycol or any combination thereof.
 11. Thecomposition according to claim 1, wherein said non-curable component isa non-water miscible compound.
 12. The composition according to claim11, wherein said non-water miscible compound is paraffin oil.
 13. Thecomposition according to claim 3, wherein said photo-initiator is a freeradical photo-initiator, a cationic photo-initiator, or any combinationthereof.
 14. The composition according to claim 1, further comprising afiller.
 15. The composition according to claim 14, wherein said fillercomprises particles having an average diameter of less than 100 mm. 16.The composition according to claim 1, further comprising asulfur-containing component.
 17. The composition according to claim 1,further comprising a low molecular weight polymer.
 18. The compositionaccording to claim 17, wherein said sulfur containing component is betamercaptopropionate, mercaptoacetate, alkane thiols or any combinationthereof.
 19. The composition according to claim 1, further comprising apigment, a dye or a combination thereof.
 20. The composition accordingto claim 19, wherein said pigment is a white pigment, an organicpigment, an inorganic pigment, a metal pigment or a combination thereof.21. The composition according to claim 1, wherein said first viscosityis about 30-200 cps.
 22. The composition according to claim 1, whereinsaid second viscosity is lower than 20 cps.
 23. The compositionaccording to claim 1, wherein said second viscosity is between 10 and1.7 cps.
 24. The composition according to claim 1, wherein said secondviscosity is between 12 and 16 cps.
 25. The composition according toclaim 1, further comprising a component able to produce gas uponexposure to water or to an alkaline or acidic water solution.
 26. Thecomposition according to claim 25, wherein said component is sodiumbicarbonate, calcium bicarbonate or a combination thereof.